Mould for electroslag remelting furnace

ABSTRACT

A mould for an electroslag remelting furnace fitted with a slag hole which is closed with a plug manufactured of a refractory material having high chemical resistance against attack by the slag. A preferred refractory material is graphite, having a specific gravity less than that of the slag.

nited States Patent [191 Medovar et al.

[4 1 Feb. 26, 1974 MOULD FOR ELECTROSLAG REMELTING FURNACE [76] Inventors: Boris Izrailevich Medovar, bulvar Leis Ukrainki, 2, kv. 8; Jury Fedorovich Alferov, bulvar Lepse, 29, kv. 6 4; Grigory Bentsionovich Schupak, ulitsa Chudnovskogo, 7, kv. 61; Valery Evgenievich Lanevsky, ulitsa V.Kuchera, 2a, kv. 8; Vitaly Grigorievich Dykan, ulitsa Ushinskogo, 8, kv. 29; Mikhail Elevich Berezovsky, ulitsa Lomonosova, 21/14, kv. 54; Vitaly Mikhailovich Baglai, ulitsa Semashko, 10, kv. 54/3; Lev Andreevich Shuruev, ulitsa Gagarina, 10/2, kv. 7; July Georgievich Emelyanenko, ulitsa Darvina, 5, kv. 5, all of Kiev; Kim

' Moiseevich Khasin, prospekt K.Marxa, 35, kv. l7, Novosibirsk; Vladimir Ivanovich Lugovsky, ulitsa Pamirskaya, 48, kv. 70, Novosibirsk; Valery Vasilievich Salmin, ulitsa Zorge, 95, kv. 69, Novosibirsk; Vilen Fedorovich Marjuschenko, ulitsa Televizionnaya, 11, kv. 7, Novosibirsk; Fedor Fedorovich Shaburov, ulitsa Rimskogo-Korsakova, 4a, kv. 64,

' Novosibirsk; Georgy Vasilievich Tamozhnikov, ulitsa Vertkovskaya, 14, kv. 4, Novosibirsk; Viktor Andreevich Popov, ulitsa Andreevskaya, l1, kv. 2, Kiev;

Gennady Mikhailovich Semin-Vadov, ulitsa Butyrskaya, 86

B, kv. 10, Moscow, all of U.S.S.R.

[22] Filed: Sept. 27, 1972 21 App]. No; 292,803

Primary Examiner.l. Spencer Overholser Assistant Examiner.l0hn E. Roethel Attorney, Agent, or Firm-Holman & Stern [57] ABSTRACT A mould for an electroslag remelting furnace fitted with a slag hole which is closed with a plug manufactured of a refractory material having high chemical resistance against attack by the slag. A preferred refractory material is graphite, having a specific gravity less than that of the slag.

4 Claims, 1 Drawing Figure MOULI) FOIR ELECTROSLAG REMELTING FURNACE BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to moulds employed in electroslag remelting furnaces. Such moulds are intended for shaping a consumable electrode being remelted into a metal ingot.

During the electroslag remelting process maintained above the head of the ingot being formed are a metal and a slag bath. On completion of the process the consumable electrodes are cut off and the ingot is cooled down by holding it in the mould being cooled until both the metal and the slag solidify completely in the upper portion of the ingot.

If the slag bath is large the ingot should be held in the mould for up to 4-8 hrs to provide solidification of the metal.

Subsequent separation of the solidified slag from the ingot is a labour-consuming operation requiring extra time and equipment.

Ingots up to l() t. and over in weight have, in terms of their volume, relatively large metal and slag baths. Insofar as metal is superior to slag in thermal conductivity, solidification of a metal bath takes substantially less time as compared to a slag bath when the electroslag remelting of the consumable electrodes is completed.

In that case the holding time of an ingot in a mould is determined not by the time interval required for the solidification of molten metal but by that for crystallization of molten slag.

Thus, after a -t. ingot has been built-up by the electroslag remelting technique, crystallization of the liquid metal requires one hour only whereas for solidification of the slag located under the metal more than 3.5 hrs are required. If the ingot is extracted earlier, the liquid slag could break through the slag skin and cause emergency conditions.

Hence, the present-day electroslag remelting technique of consumable electrodes into heavy ingots-involves forced stoppages which may reach several hours per heating period.

Moreover, prolonged cooling of the ingot in the mould impairs the quality of the metal, especially in the bottom part of the ingot. Where self-hardening steels are remelted, it may lead to the origination of cold cracks in the ingot produced of such materials.

Attempts have been made to remove the liquid slag from the mould as soon as the electroslag process was completed. To do that it was suggested to remove the liquid slag from the head of the ingot either by siphoning or by forcing it out such as, by immersion of a wider part of a stub into the slag. I

This makes it possible to somewhat reduce the slag removal time although it necessitates the use of additional facilities.

Known in the art is an injection slagging process for I removing slag from slagmelting furnaces. The known process suffers from a disadvantage which lies in that it requires too large appliances and too large an input of labour in carrying out the process.

At present the moulds employed for performing the electroslag process are not provided with arrangements for flushing the liquid slag.

It is an object of the present invention to overcome the above difficulties.

The principal object of this invention is to develop a mould with a slagging means which will provide for rapid and reliable removal of slag.

Still another no less important object of the invention is to increase the operating hours of the furnace by reducing its idle time attributable to the removal of slag from the mould.

A further object of the invention is the concurrent remelting of several consumable electrodes in a mould adapted for slagging.

Yet another object of the invention is to provide mechanized removal of a plug from a slag hole provided in a mould wall.

The above objects are achieved by developing a mould for an electroslag remelting furnace with mould walls bounding a cavity for metal and slag baths, in which mould, according to the invention in the slag bath zone the mould wall is fitted with a tap hole for pouring off the slag, referred to hereinafter as a slag hole, the tap hole being sealed with a plug produced from refractory material featuring high chemical resistance against the slag attack, such as graphite whose specific gravity is less than that of the slag.

The above mould would enable rapid and complete removal of the liquid slag from the upper portion of the ingot thus reducing thereby unproductive idle time of the furnace.

The mould is preferably made of split construction with a joint along the horizontal plane and with said slag hole being made in its upper widened detachable part.

The detachable widened part of the mould is convenient in case of replacement and affords the use of a different number of electrodes, the ratio of the total area of their cross sections to the area of the ingot being melted ranging from 0.8 to 1.2.

It is desirable to fit the mould with an arrangement for example, with a pneumatic percussive mechanism to tap the plug from said slag hole.

This will enable mechanization of the plug removal from the slag hole.

A fuller understanding of the invention will be had from the following description of an exemplary embodiment taken in conjunction with the accompanying drawing in which:

FIG. I is a longitudinal section by a vertical plane of a mould according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A mould 1 for an electroslag remelting furnace (not shown in the drawing) is fitted with water-cooled walls 2 forming a cavity 3 for an ingot and a slag bath 4. An upper part of the mould 1 may be made detachable and enlarged (widened) as compared to the lower one. It is.

designed to retain the slag bath 4. Provided in the wall of the mould l in the zone of the slag bath 4 is a slag hole 6 closed with a plug 7 made from refractory material chemically resistant against the slag attack, for instance, graphite whose specific gravity is less than that of the slag.

For tapping the plug 7 from the said hole 6 use may be made of a pneumatic percussive mechanism 8, the slag being directed to a receptacle (not shown in the drawing) along a spout 9 whose working surface is coated with graphite.

The mould functions in the following manner:

Melting being completed, a pneumatic percussive mechanism 8 is engaged which knocks out or taps a graphite plug 7 from a slag hole 6. Next the pneumatic percussive mechanism 8 is returned into its original position, the plug 7 floats up and slag is flushed from the mould 1 to a receptable along a spout 9.

We claim:

1. A mould for an clectroslag remelting furnace comprising: walls bounding a cavity for metal and slag baths; a slag hole provided in the wall of said mould in the zone of the slag bath and a plug closing said slag 

1. A mould for an electroslag remelting furnace comprising: walls bounding a cavity for metal and slag baths; a slag hole provided in the wall of said mould in the zone of the slag bath and a plug closing said slag hole and produced from refractory material, featuring adequate chemical resistance against the slag attack and a lower specific gravity as compared with that of the slag.
 2. A mould of claim 1 which is made detachable along the horizontal plane, said slag hole being provided in the upper widened detachable part.
 3. A mould of claim 1 fitted with an arrangement which is a pneumatic percussive mechanism for tapping said plug from said slag hole.
 4. A mould of claim 1 wherein the refractory material is graphite. 